1. Field of the Invention
The present invention relates to a silicone water-based emulsion composition which provides a water-repellent material which cures upon the removal of water to afford a rubbery elastomer.
2. Background Information
A number of water-repellent silicon water-based emulsion compositions which are cured into rubbery elastomers after the removal of water have been proposed or provided in the prior art. U.S. Pat. No. 3,355,406, issued Nov. 28, 1967, teaches silicone rubber latexes reinforced by adding silsesquioxane. In example 19, a composition of hydroxyl endblocked polydiorganosiloxane, silsesquioxane, methylhydrogenpolysiloxane, and dibutyltin dilaurate is taught. Upon evaporation of the water from a film of the latex, a silicone rubber film was left. U.S. Pat. No. 4,221,688, issued Sept. 9, 1980, (equivalent to Japanese Patent Application Laid Open Number 56-16553 [16,553/81]) proposes a silicone water-based emulsion composition which is based on hydroxyl group-terminated diorganopolysiloxane, colloidal silica, and an alkyltin salt. U.S. Pat. No. 4,427,811, issued Jan. 24, 1984, (Japanese Patent Application Laid Open Number 58-118853 [118,853/83]) discloses an improved method for producing a high solids silicone water-based emulsion composition.
However, a number of problems arise in connection with these prior water-repellent silicone water-based emulsion compositions. Thus, their cured coatings are not resistant to alkali, and their adhesive strength will decline with time and the physical properties of the coatings themselves will deteriorate when they are applied on alkaline substrates such as concrete, etc. Also, these prior water-repellent silicone water-based emulsion compositions have poor storage stabilities, and the cured coatings obtained after prolonged periods of storage will have high hardnesses and thus reduced elongations.
Accordingly, the present inventors conducted research with a view to eliminating the above problems, and the present invention was developed as a result.